Detection rules › Sublime MQL

Link: Adobe share from unsolicited sender

Severity
medium
Type
rule
Source
github.com/sublime-security/sublime-rules

This attack surface reduction rule matches on messages from Adobe which were sent by an email address (as determined by the sender display name) which doesn't appear to have a relationship with the recipient organization.

Threat classification

Sublime's own taxonomy (not MITRE ATT&CK).

CategoryValues
Attack typesCredential Phishing
Tactics and techniquesFree file host, Evasion

Event coverage

Rule body MQL

type.inbound
// from Adobe Actual
and strings.icontains(sender.display_name, 'via Adobe')
and sender.email.email == 'message@adobe.com'
and headers.auth_summary.dmarc.pass
// contains a link to open or review a share
and any(body.links, .display_text =~ "open" or .display_text =~ "review")
// attempt to ensure the sender (from the sender.display_name) does NOT have a relationship with to recipient org

// not sent from a Adobe User within the org's domains
and not any($org_domains,
            strings.icontains(sender.display_name,
                              strings.concat("@", ., ' via Adobe')
            )
)
// the org has never sent a message to the address within the sender.display_name
and not any($recipient_emails, strings.istarts_with(sender.display_name, .))

Detection logic

Scope: inbound message.

This attack surface reduction rule matches on messages from Adobe which were sent by an email address (as determined by the sender display name) which doesn't appear to have a relationship with the recipient organization.

  1. inbound message
  2. sender.display_name contains 'via Adobe'
  3. sender.email.email is 'message@adobe.com'
  4. headers.auth_summary.dmarc.pass
  5. any of body.links where any holds:
    • .display_text is 'open'
    • .display_text is 'review'
  6. not:
    • any of $org_domains where:
      • strings.icontains(sender.display_name)
  7. not:
    • any of $recipient_emails where:
      • strings.istarts_with(sender.display_name)

Inspects: body.links, body.links[].display_text, headers.auth_summary.dmarc.pass, sender.display_name, sender.email.email, type.inbound. Sensors: strings.concat, strings.icontains, strings.istarts_with. Reference lists: $org_domains, $recipient_emails.

Indicators matched (4)

FieldMatchValue
strings.icontainssubstringvia Adobe
sender.email.emailequalsmessage@adobe.com
body.links[].display_textequalsopen
body.links[].display_textequalsreview